Lancing device

ABSTRACT

A lancing device (A) includes an auxiliary member ( 8 ) located on a side of the tip end portion of a lancet (L). By moving the auxiliary member ( 8 ), the dimension (s) of the tip end of the lancet (L) projecting from the tip end portion ( 8   a ) of the auxiliary member ( 8 ) can be varied. The variation of the dimension (S) makes it possible to stick the lancet (L) into the skin ( 99 ) of a user precisely by an intended amount.

TECHNICAL FIELD

The present invention relates to a lancing device used for sticking atip end of a lancet into skin for taking blood or other body fluid ortissue for examination.

BACKGROUND ART

An example of prior art lancing device is disclosed in JP-A-11-9577. Asshown in FIG. 16, the prior art device includes a generally cylindricalhousing 90 and a lancet holder 92 arranged in the housing for holding alancet L. A cylindrical plunger 93 is fitted into one end of the housing90. In this prior art device, when the plunger 93 is pushed in the arrowN1 direction, the lancet holder 92, which has latched on a predeterminedportion in the housing 90, is forced to be released from the latchedstate. As a result, the lancet holder 92 advances toward a tip endopening 90 a of the housing 90 due to the resilient force of a spring95. As shown in FIG. 16C, a tip end surface 90 b of the housing 90 ispressed against skin 99, so that the advancing movement of the lancetholder 92 causes the tip end of the lancet L to stick into the skin 99.

The housing 90 comprises two sleeves 90A and 90B connected to eachother. The sleeve 90A is movable relative to the sleeve 90B in the axialdirection (arrow N2 direction) of the housing 90. Specifically, as shownin FIG. 16B, the sleeve 90A has an inner circumferential surfaceprovided with an inclined surface 90 c. When the sleeve 90A is rotated,the inclined surface 90 c engages with a predetermined member, whichallows positional adjustment of the sleeve 90A in the arrow N2direction.

In such a structure, as shown in FIG. 16 c, by adjusting the position ofthe sleeve 90A, it is possible to vary the dimension s1 of the lancet Lprojecting from the tip end surface 90 b of the housing 90 when thelancet L is advanced toward the tip end of the housing 90. Therefore,the sticking amount of the lancet L relative to the skin 99 is variable.

However, the prior art device has the following problems.

When the tip end surface 90 b of the housing 90 is pressed against theskin 99 with a small force, the skin 99 is generally flush with the tipend surface. However, as shown in FIG. 17, when the pressing forcerelative to the skin 99 is strong, the skin 99 enters the tip endopening 90 a of the housing 90. The entering amount is not constant butvaries depending on the softness of the skin 99. In sticking the lancetL, negative suction pressure may often be exerted on the portion to bestuck to cause bleeding from that portion. Also in such a case, theentering amount is not constant.

However, the prior art device described above can adjust only thedimension s1 of the lancet L projecting from the tip end surface 90 b ofthe housing 90. Therefore, the sticking amount into the skin 99 by thelancet L differs between the case where the skin 99 is flush with thetip end surface 90 b as shown in FIG. 16C and the case where the skin 99enters the tip end opening 90 a as shown in FIG. 17. Further, in thecase where the skin 99 enters the tip end opening 90 a, the stickingamount of the lancet L varies depending on the entering amount s2. Thus,with the prior art device, sticking of the lancet L into the skin justby an intended amount is difficult. As a result, due to excess orinsufficient sticking amount of the lancet L, there have been suchproblems that the skin is hurt more than necessary or the amount ofbleeding from the portion stuck by the lancet L is insufficient.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a lancing device whichcan eliminate or lessen the above-described problems.

A lancing device provided according to the present invention comprises ahousing having a tip end formed with an opening, a lancet arranged inthe housing, an operation mechanism for making the lancet movable toadvance from within the housing toward the opening, and an auxiliarymember for advancing together with the lancet toward the opening, theauxiliary member having a tip end portion located on a side of a tip endportion of the lancet, the auxiliary member being capable of varying aposition relative to the lancet for varying a projecting dimension ofthe tip end portion of the lancet from the tip end portion of theauxiliary member.

Herein, the side of the tip end portion of the lancet means at least apart of the circumference of the tip end portion of the lancet.

In a preferred embodiment, the housing includes a sleeve rotatablerelative to another portion of the housing, and the variation of theposition of the auxiliary member relative to the lancet is performed byrotating the sleeve.

In a preferred embodiment, the lancing device includes a cam mechanismwhich moves the auxiliary member in a back-and-forth direction of thelancet when the auxiliary member is rotated relative to the lancet, andthe auxiliary member engages the sleeve to rotate relative to the lancetby rotating the sleeve.

In a preferred embodiment, the device further comprises a lancet holderfor removably holding the lancet, and the advancing movement of thelancet is performed by moving the lancet holder by an operation of theoperation mechanism.

In a preferred embodiment, the auxiliary member is attached to thelancet holder.

In a preferred embodiment, the auxiliary member and the lancet holderare attached together by threading engagement, and the variation of theposition of the auxiliary member relative to the lancet is performed byrotating the auxiliary member and the lancet holder relative to eachother.

In a preferred embodiment, the tip end portion of the auxiliary membersurrounds an entire circumference of the tip end portion of the lancet.

In a preferred embodiment, the lancet includes a main body and a needleprojecting from a tip end surface of the main body, and the tip endportion of the auxiliary member is provided with a patch plate portionfacing the tip end surface of the main body. The patch plate portion isformed with a hole for passing the needle.

In a preferred embodiment, the auxiliary member has a configurationcapable of allowing the needle of the lancet to project from the tip endportion of the auxiliary member entirely throughout the length.

In a preferred embodiment, the operation mechanism comprises a resilientmember for biasing the lancet holder in the housing toward the opening,a latch member for latching the lancet holder in the housing againstresilient force of the resilient member, an operation member exposed toan outside of the housing at least partially, and a latch release memberwhich operates to release the lancet holder from the latched state whenthe operation member is operated.

In a preferred embodiment, the device further comprises a pumpmechanism. The pump mechanism comprises a cylinder and a plungerdefining a pressure chamber capable of communicating with an outside ofthe housing through an exhaust vent and capable of communicating with aninside of the tip end portion of the housing through an intake vent, aplunger operation mechanism for reciprocally moving the plunger relativeto the cylinder by an operation different from the operation of theoperation mechanism, a first non-return valve for opening or closing theexhaust vent, the first non-return valve keeping the exhaust vent openwhen the plunger reduces a volume of the pressure chamber, and a secondnon-return valve for opening or closing the intake vent, the secondnon-return valve keeping the intake vent open when the plunger increasesthe volume of the pressure chamber.

In a preferred embodiment, the plunger operation mechanism comprises anouter cylinder arranged outwardly on the housing for reciprocalmovement, and connecting means for connecting the plunger to the outercylinder so that the plunger moves reciprocally relative to the cylinderwhen the outer cylinder moves reciprocally.

Other features and advantages of the present invention will becomeclearer from the description of the embodiments of the present inventiongiven below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating an example of lancing deviceaccording to the present invention.

FIG. 2 is a sectional view taken along lines II—II in FIG. 1.

FIG. 3 is a sectional view taken along lines III—III in FIG. 2.

FIG. 4 is an enlarged perspective view, partially in section,illustrating a principal portion of the lancing device of FIG. 1.

FIG. 5 is an enlarged sectional view illustrating a principal portion ofFIG. 3.

FIG. 6 illustrates the operation of the portion shown in FIG. 5.

FIGS. 7A and 7B are sectional views illustrating the operation inproducing negative pressure.

FIG. 8 is a sectional view illustrating the advancing movement of thelancet.

FIG. 9 is a sectional view illustrating a principal portion in a statewhere the lancet is stuck into the skin.

FIG. 10 is a sectional view of a principal portion in a state where theprojecting amount of the lancet from the tip end portion of theauxiliary member is made large.

FIG. 11 is a sectional view illustrating the operation in eliminatingnegative pressure.

FIG. 12 is a perspective view, partially in section, illustrating aprincipal portion of another embodiment of the present invention.

FIG. 13A is a perspective view illustrating a principal portion ofanother embodiment of auxiliary member, and FIG. 13B is a sectional viewtaken along lines XIII—XIII in FIG. 13A.

FIG. 14 is a perspective view illustrating a principal portion ofanother embodiment of auxiliary member.

FIG. 15 is a sectional view illustrating a principal portion of anotherembodiment of auxiliary member mounting structure.

FIG. 16A is a sectional view illustrating an example of prior artdevice, FIG. 16B is a perspective view of a part of the prior artdevice, and FIG. 16C is a sectional view of a principal portion of theprior art device for illustrating the operation.

FIG. 17 is a sectional view of a principal portion of the prior artdevice for illustrating the operation.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present invention will be described belowin detail with reference to the accompanying drawings.

FIGS. 1-11 illustrate an example of a lancing device according to thepresent invention. As shown in FIG. 2, the lancing device A in thisembodiment includes a housing 1, an outer cylinder 2, a lancet holder 3for removably holding a lancet L, an auxiliary member 8 attached to thelancet holder 3, a latch mechanism 4 for the lancet holder 3, and a pumpmechanism 5 defining a pressure chamber 53 for producing negativepressure. The lancet L comprises a generally columnar main body 98 aformed of e.g. synthetic resin and a metal needle 98 b projecting fromthe tip end surface of the main body. Preferably, for good hygiene, thelancet L is used only once and disposed after use.

The housing 1 comprises, for example, three sleeves 10 a-10 c connectedto each other in series and has a generally cylindrical configurationhaving a tip end formed with an opening 11. The sleeve 10 a constitutesa portion of the housing 1 adjacent to the tip end and is rotatablerelative to the sleeve 10 b. The sleeve 10 a has a tip end 10 a′ to bepressed against a user's skin and is removable from the sleeve 10 b.Such removable arrangement of the sleeve 10 a makes it possible toreplace the sleeve 10 a with a new one when sampled body fluidaccidentally adheres to this sleeve.

The lancet holder 3 has a tip end portion provided with a generallycylindrical holding piece 39 for holding the main body 98 a of thelancet L fitted therein. The lancet holder 3 is reciprocally movable inthe axial direction Ng of the housing 1 (corresponding to theback-and-forth direction of the lancet L) and can be latched on apredetermined position in the housing 1 by the latch mechanism 4. Thelancet holder 3 can move forward toward the opening 11 when it isreleased from the latched state. The structure will later be describedin detail.

The auxiliary member 8, which is generally cylindrical, is rotatablyarranged outwardly on the tip end portion of the lancet holder 3 tosurround the outer circumference of the lancet L almost throughout itslength while being slidably fitted to a generally cylindrical guidemember 36 provided in the tip end portion of the housing 1. Theauxiliary member 8 has a tip end portion 8 a, which engages with theuser's skin 99 in sticking the lancet L into the skin 99 and which hasan outer diameter smaller than the inner diameter of the opening 11 ofthe tip end of the housing 1. In detaching the sleeve 10 a from thesleeve 10 b, the sleeve 10 a holds the auxiliary member 8 together withthe guide member 36 so as not to hinder the attaching or detaching ofthe lancet L relative to the lancet holder 3. When at least portionsadjacent to the tip end of the guide member 36 and the sleeve 10 a aremade transparent, bleeding from the portion where the lancet L is stuckcan be checked visually. The present invention may employ such astructure.

The auxiliary member 8 is upwardly provided with an engagementprojection 81 engaging with a groove 19 formed at an inner wall surfaceof the sleeve 10 a. Therefore, as clearly shown in FIG. 4, when thesleeve 10 a is rotated in the arrow Nh direction, the auxiliary member 8rotates together with the sleeve in the same direction. The auxiliarymember 8 and the lancet holder 3 constitute a cam mechanism C. The cammechanism C comprises a cam surface 89 formed at the upper end of theauxiliary member 8 and including a surface inclined relative to theaxial direction NG of the housing 1, and a projection 38 formed at anouter surface of the lancet holder 3 for engagement with the cam surface89. In the cam mechanism C, when the auxiliary member 8 is rotated inthe arrow Nh direction, the engaging position of the projection 38relative to the cam surface 89 deviates to move the auxiliary member 8in the axial direction Ng of the housing 1. The groove 19 extends in theaxial direction Ng of the housing 1 for allowing the movement of theauxiliary member 8 in that direction. The tip end portion of the housing1 is inwardly provided with a spring 65 for pushing the auxiliary member8 toward a head of the housing 1 with a relatively small force so as nothinder the advancing movement of the lancet holder 3 (See FIG. 2). Theresilient force of the spring 65 keeps the engagement between the camsurface 89 and the projection 38 so that the auxiliary member 8 isreciprocally movable in the axial direction Ng of the housing 1 inaccordance with the movement of the lancet holder 3.

In the lancing device A, since the auxiliary member 8 is movablerelative to the lancet holder 3 in the axial direction Ng of the housing1, the tip end portion of the lancet L can be caused to project downwardfrom the tip end portion 8 a of the auxiliary member 8 as clearly shownin FIGS. 2 and 3, and the projecting amount S can be adjusted. Asclearly shown in FIG. 1, outer circumferential surfaces of the sleeves10 a and outer cylinder 2 are formed with a reference line 18 a and aplurality of scales 18 b, respectively, as marks for adjusting theprojecting amount S.

In the present invention, a mechanism as shown in FIG. 12 may be usedinstead of the above-described mechanism for making the auxiliary member8 rotate together with the rotation of the sleeve 10 a. In the mechanismshown in the figure, the tip end portion 8 a of the auxiliary member 8has an outer circumference surface formed with a projection 80. Theprojection 80 is fitted in a slit 36 b defined between a pair of plateportions 36 a of the guide member 36, thereby engaging each of the plateportions 36 a. With this structure, when the sleeve 10 a and the guidemember 36 are rotated in the arrow Nh direction by operating the sleeve10 a, the auxiliary member 8 also rotates together with these members.Therefore, by the operation of the cam mechanism C, the auxiliary member8 moves relative to the lancet holder 3 in the axial direction Ng of thehousing 1. The projection 80 of the auxiliary member 8 is movable in theslit 36 b in the axial direction Ng of the guide member 36 for allowingproper movement of the auxiliary member 8 in the axial direction of thehousing 1. When this structure is utilized, unlike the structure shownin FIG. 4, it is not necessary to form the groove 19 at the inner wallof the sleeve 10 a, which simplifies the structure of the apparatus.

As clearly shown in FIG. 2, the outer cylinder 2 is arranged outwardlyon the housing 1 for reciprocal sliding movement in the axial directionNg. After the outer cylinder 2 is pushed downward relative to thehousing 1, the outer cylinder 2 returns to its original position due tothe resilient force of a spring 60. Specifically, an innercircumferential surface of the outer cylinder 2 at the upper portion andan outer circumferential surface of the housing 1 at the axiallyintermediate portion are provided with stepped portions 20 and 12,respectively, which define a gap between the outer cylinder 2 and thehousing 1. The spring 60 is arranged in this gap. The spring 60, whichis a coil compression spring, functions to return not only the outercylinder but also a plunger 51 upward, which will be described later.

The pump mechanism 5 comprises a cylinder 50, the plunger 51 and a firstand a second non-return valves 52A, 52B. The cylinder 50 and the plunger51 define the pressure chamber 53. The cylinder 50 is fitted in an upperportion of the housing 1 for reciprocal movement within a predeterminedstroke. The cylinder 50 and the plunger 51 define the pressure chamber53. The cylinder 50 is fitted in an upper portion of the housing 1 forreciprocal movement within a predetermined stroke. The cylinder 50 hasan upper portion to which a head cap 76 for pushing operation isattached to project higher than the upper end of the outer cylinder 2.When the head cap 76 is pushed down, the cylinder 50 also movesdownward. The head cap 76 is an example of operation member in thepresent invention. A spring 61 is arranged below the cylinder 50 so thatthe cylinder 50 after pushed down can return to its original positiondue to the resilient force of the spring 61. The spring 61 is supportedby a sleeve 40, which will be described later.

The plunger 51 is fitted in the cylinder 50 for reciprocal slidingmovement. As clearly shown in FIG. 3, the plunger 51 is provided with apair of arms 51 a, which are connected to an upper portion of the outercylinder 2. Therefore, when the outer cylinder 2 moves reciprocally inthe axial direction Ng of the housing 1, the plunger 51 correspondinglymoves reciprocally in the cylinder 50. In this embodiment, the outercylinder 2 constitutes a plunger operation mechanism in the presentinvention. The cylinder 50 is provided with cutouts for avoiding itsinterference with the arms 51 a.

The plunger 51 is provided with an exhaust vent 54 for discharging airexisting in the pressure chamber 53 to the outside of the housing 1. Thefirst non-return valve 52A, which is attached to the plunger 51, isprovided with a flexible collar for opening or closing the exhaust vent54. The first non-return valve 52A allows air flow from within thepressure chamber 53 to the outside of the housing 1, but blocks air flowinto the pressure chamber 53 from the outside.

The cylinder 50 has a bottom portion provided with an intake vent 55 forcausing air existing in the housing 1 to flow into the pressure chamber53. A continuous communication path is formed in the housing 1 forproviding communication between the intake vent 55 and the interior ofthe tip end portion of the housing 1. Specifically, as clearly shown inFIG. 2, the intake vent 55 communicates with the interior of the tip endportion of the housing 1 via through-holes provided respectively at afirst and a second push members 41 and 42 which will be described later,a plurality of slits 30 provided at an upper portion of the lancetholder 3, and a gap 70 defined between a stepped portion 13 of thehousing 1 and the lancet holder 3.

The second non-return valve 52B, which serves to open or close theintake vent 55, is also provided with a flexible collar similarly to thefirst non-return valve 52A. The second non-return valve 52B allows airflow from the outside of the pressure chamber 53 into the pressurechamber 53, but blocks air flow from the inside of the pressure chamber53 to the outside.

As clearly shown in FIG. 5, the latch mechanism 4 comprises the sleeve40 and the first and the second push members 41, 42 reciprocally fittedin the sleeve 40. The sleeve 40, which is an example of latch member inthe present invention, has a flange 40 a sandwiched between the twosleeves 10 b and 10 c of the housing 1, thereby being fixed in thehousing 1 below the cylinder 50. The sleeve 40 has a lower portionformed with a pair of holes 40 b for engagement with a pair of latchengagement pawls 31 formed at an upper end portion of the lancet holder3. The upper portion of the lancet holder 3 is provided with a spring 62as a coil pressure spring having an upper end engaging the second pushmember 42. The lancet holder 3 can latch on the sleeve 40 by theengagement of each engagement pawl 31 with the relevant hole 40 b withthe spring 62 compressed. The latching can be performed by manuallypushing the lancet holder 3 upwardly in the housing 1 after the lancet Lis attached to the lancet holder.

The first push member 41 is connected to the bottom portion of thecylinder 50 for reciprocal movement together with the cylinder 50. Thefirst push member 41 has a lower portion fitted in the sleeve 40. Thesecond push member 42 has an upper portion fitted in the sleeve 40 forreciprocal movement therein and engaging the bottom surface of the firstpush member 41 due to the resilient force of the spring 62. The secondpush member 42, which is an example of latch release member in thepresent invention, has a pair of projections 42 a respectively locatedabove the engagement pawls 31 of the lancet holder 3. Each of theprojections 42 a and each of the engagement pawls 31 are provided withpredetermined tapered surfaces corresponding to each other. Thus, whenthe projections 42 a are moved downward to a position lower than thestate shown in FIG. 5, the projections 42 a push the respectiveengagement pawls 31 for deformation toward the center of the housing 1,i.e. in the direction indicated by the arrow Na. As a result, theengagement pawls 31 are disengaged from the sleeve 40.

The first push member 41 is provided with an O-ring 41 a formed ofrubber for achieving airtightness between the first push member 41 andthe inner circumferential surface of the sleeve 40. The innercircumferential surface of the sleeve 40 is provided with a steppedportion 49 so that, in moving the push member 41 downward by pushing thehead cap 76, the resistance relative to the pushing operation varies.Specifically, the inner diameter D1 at an upper portion of the sleeve 40is slightly larger than the inner diameter D2 at a lower portion of thesleeve. It is set so that, in the case where the O-ring 41 a movesdownward together with the first push member 41, the O-ring 41 a justcomes to the stepped portion 49 when the second push member 42disengages the engagement pawls 31 from the sleeve 40. As clearly shownin FIG. 6, the first push member 41 can move downward until the O-ring41 a finishes passing the portion having the inner diameter D2, but insuch a state, the portion where the first push member 41 and the sleeve40 fit to each other is released from the airtight state.

Next, the usage and operation of the lancing device A will be described.

As shown in FIGS. 2 and 3, for using the lancing device A, a lancetholder 3 holding a lancet L is first latched on the sleeve 40.Subsequently, as shown in FIG. 1, with the tip end of the housing 1brought in contact with a user's skin 99, the outer cylinder 2 is movedreciprocally upward and downward. This operation can be performedeasily, because the outer cylinder 2 is easy to hold and the outercylinder 2 moves upward due to the resilient force of the spring 60.

As clearly shown in FIG. 7A, when the outer cylinder 2 moves downward inthe arrow Nb direction, the plunger 51 also moves downward. At thattime, the second non-return valve 52B is closed, whereas the firstnon-return valve 52A is open, so that air in the pressure chamber 53 isdischarged to the outside of the housing 1 through the exhaust vent 54.As shown in FIG. 7B, when the outer cylinder 2 then moves upward in thearrow Nc direction, the plunger 51 also moves upward. As a result, thevolume of the pressure chamber 53 increases to produce negative pressurein the pressure chamber 53. At that time, the first non-return valve 52Ais closed, whereas the second non-return valve 52 is open. Therefore,negative pressure is also produced in the tip end portion of the housing1, and the negative pressure acts on the skin 99.

In the case where the outer cylinder 2 is further moved reciprocallyfollowing the above-described operation, negative pressure in the tipend portion of the housing 1 is properly maintained because the secondnon-return valve 52B is closed when the plunger 51 moves downward.Therefore, as the reciprocal movement of the outer cylinder 2 isrepeated, negative pressure in the pressure chamber 53 and in the tipend portion of the housing 1 is gradually increased (the absolutepressure is decreased). Thus, in the lancing device A, the negativepressure to be exerted on the skin 99 can be appropriately controlled byincreasing or decreasing the number of times of the reciprocal movementof the outer cylinder 2.

Subsequently, to stick the lancet L into the skin 99, the head cap 76 isdepressed with fingers. This operation causes the cylinder 50 and thefirst and the second push member 41, 42 to move downward. The secondpush member 42 pushes each engagement pawl 31 of the lancet holder 3 sothat the lancet holder 3 is released from its latched state on thesleeve 40. As a result, as clearly shown in FIG. 8, the lancet holder 3advances quickly in the arrow Nd direction toward the opening 11 at thetip end of the housing 1, and the tip end portion of the lancet L sticksinto the skin 99. When the head cap 76 is further depressed from thisstate, the O-ring 41 a of the first push member 41 shown in FIG. 5 movesfrom the portion with the inner diameter D1 to the portion with theinner diameter D2 of the sleeve 40. Therefore, the resistance to thepushing operation of the head cap 76 increases, which duly notifies theuser that the advancing movement of the lancet L described above iscompleted.

As clearly shown in FIG. 9, when the tip end portion of the lancet Lsticks into the skin 99, the tip end portion 8 a of the auxiliary member8 comes into contact with the skin 99. Thus, the auxiliary member 8serves as a stopper to prevent the lancet holder 3 and the lancet L fromadvancing over a predetermined distance. Therefore, among the tip endportion of the lancet L, only a portion (having a dimension S)projecting downward from the tip end portion 8 a of the auxiliary member8 sticks into the skin 99. The sticking amount is generally equal to thedimension S regardless of the dimension of the skin entering the opening11 at the tip end of the housing 1 due to negative pressure. Thesticking amount can be made much closer to the above-described dimensionS by making the diameter of the opening at the tip end portion of theauxiliary member 8 smaller and hence closer to the diameter of theneedle 98 b.

The dimension S described above can easily be varied by rotating thesleeve 10 a. Therefore, the sticking amount of the lancet L into theskin 99 can appropriately be varied depending on such conditions thatthe portion to be stuck with the lancet L is likely to bleed or not.Thus, it is possible to eliminate such problems that the skin 99 is hurtmore than necessary or bleeding is difficult due to insufficient amountof sticking by the lancet L. The setting of dimension S can be performedby referring to the reference line 18 a and the scales 18 b shown inFIG. 1, which is convenient.

In this embodiment, the opening diameter at the tip end portion of theauxiliary member 8 is made larger than the main body 98 a of the lancetL. Therefore, as shown in FIG. 10, the needle 98 b of the lancet L canproject entirely from the tip end portion 8 a of the auxiliary member 8.Contrarily to this, the projecting amount S can be made close to zero.Thus, the sticking amount can be adjusted within a wide range, whichprovides further convenience. After the lancet L sticks into the skin99, the lancet holder 3 can be retreated by an appropriate amount byutilizing the resilient force of the spring 65.

When the head cap 76 is further depressed as shown in FIG. 11, theO-ring 41 a moves down to a position after passing through the portionof the sleeve 40 having the diameter D2. As a result, the communicationpath extending from the tip end portion of the housing 1 to the intakevent 55 of the cylinder 50 is released from the airtight state, so thatthe interior of the tip end portion of the housing 1 returns toatmospheric pressure. Therefore, the housing 1 can be easily removedfrom the skin 99.

The elimination of negative pressure described above can be performedonly after the lancet L is stuck into the skin 99. Therefore, negativepressure acting on the skin 99 is prevented from erroneously beingeliminated before the lancet L is stuck. Therefore, it is possible toreliably perform sticking of the lancet L into the skin 99 while bulgingthe skin 99 by negative pressure and promoting blood circulation at thatportion. Both of the sticking of the lancet L and the eliminating ofnegative pressure can be easily performed by pushing down the head cap76.

In the above-described example of usage of the lancing device A, thelancet L is stuck into the skin after negative pressure is produced inthe tip end portion of the housing 1. However, such process steps inusing the lancing device A may be performed in the reverse order.Specifically, the lancet L may first be stuck into the skin bydepressing the head cap 65 and then negative pressure may be exerted onthe portion stuck by the lancet L by reciprocating the outer cylinder 2.Also with this order of process steps, negative pressure promotesbleeding from the portion stuck by the lancet L. In this way, thelancing device A is conveniently used because the user can appropriatelyselect to produce negative pressure before sticking the lancet L intothe skin or after sticking the lancet into the skin.

FIGS. 13A, 13B, 14 and 15 illustrate another embodiment of the presentinvention. In these drawings, elements which are identical of similar tothose of the above-described embodiment are designated by the samereference signs as those used in the above-described embodiment.

In the structure shown in FIGS. 13A and 13B the tip end portion 8 a ofthe auxiliary member 8 is formed with a patch plate portion 85. Thepatch plate portion 85 is generally circular and arranged in facingrelationship to a tip end surface 98 a′ of the main body 98 a of thelancet L. The patch plate portion 85 is formed with a hole 88 of a smalldiameter for passing the needle 98 b of the lancet L.

With this structure, the diameter d1 of the hole 88 is made smaller thanthe diameter d2 of the main body 98 a of the lancet L and hence closerto the diameter d3 of the needle 98 b. Therefore, the auxiliary member 8can set the sticking amount of the needle 98 b into the skin moreprecisely.

In the structure shown in FIG. 14, the auxiliary member 8 includes twoprojections 87. The two projections 87 have respective end portionslocated on the sides of the needle 98 b of the lancet L for sandwichingthe needle 98 b. In this case, when the needle 98 b of the lancet L isstuck into the user's skin, an end surface 87 a of each projection 87comes into contact with the skin to prevent the needle 98 b fromsticking into the skin more than necessary. Thus, also in this case, theobject of the present invention is attained. To precisely set thesticking amount of the lancet into the skin, it is preferable that theauxiliary member surrounds the entire circumference of the tip endportion of the lancet, but the present invention is not limited thereto.

In the structure shown in FIG. 15, the lancet holder 3 is provided witha male thread 3 a formed around the tip end portion thereof, whereas theauxiliary member 8 is provided with a female thread 86. The auxiliarymember 8 is directly attached to the lancet holder 3 by threadingengagement of the thread portions 3 a and 86. In such a structure, whenthe auxiliary member 8 is rotated, the auxiliary member 8 moves relativeto the lancet holder 3 in the arrow Nj direction by the operation of thethreads 3 a and 86. Therefore, also with this structure, it is possibleto vary the projecting amount of the tip end portion of the lancet Lfrom the tip end portion of the auxiliary member 8, so that the objectof the present invention is attained. In this way, in the presentinvention, the auxiliary member may be directly mounted to the lancetholder. In such a case, the mounting structure can be made simpler thanthe case where the auxiliary member is held by a member other than thelancet holder.

The lancing device according to the present invention is not limited tothe above-described embodiments, and the specific structure of each partmay be modified in various ways.

For example, in the present invention, the lancet may be advanced by acertain operation mechanism without using the lancet holder removablyholding the lancet. Further, in the present invention, a needle may beattached to an appropriate member reciprocally arranged in the housingfor serving as a lancet. Although it is preferable the lancet after usecan be easily replaced with a new one, such a structure is notessential.

To make the auxiliary member movable relative to the lancet, means otherthan that of the above-described embodiment may be utilized. The lancingdevice according to the present invention may not be provided with apump mechanism for producing negative pressure in the tip end portion ofthe housing. The operation mechanism in the present invention may be anymechanism if only it can advance the lancet from within the housingtoward the opening of the housing.

1. A lancing device comprising: a housing having a tip end formed withan opening; a lancet arranged in the housing, the lancet including amain body and a lancing projection protruding forwardly from the mainbody, the lancing projection having a tip end; an operation mechanismfor advancing the lancet within the housing toward the opening; and anauxiliary member for advancing together with the lancet toward theopening, the auxiliary member having a tip end portion that extendsbeyond the main body of the lancet toward the opening but is locatedshort of the tip end of the lancing projection; the auxiliary memberbeing capable of varying a position relative to the lancet for varying aprojecting dimension of the lancing projection of the lancet from thetip end portion of the auxiliary member.
 2. The lancing device accordingto claim 1, wherein the housing includes a sleeve rotatable relative toanother portion of the housing; the variation of the position of theauxiliary member relative to the lancet being performed by rotating thesleeve.
 3. The lancing device according to claim 2, further comprising acam mechanism which moves the auxiliary member in a back-and-forthdirection of the lancet when the auxiliary member is rotated relative tothe lancet; the auxiliary member engaging the sleeve to rotate relativeto the lancet by rotating the sleeve.
 4. The lancing device according toclaim 1, further comprising a lancet holder for removably holding thelancet; the advancing movement of the lancet being performed by movingthe lancet holder by an operation of the operation mechanism.
 5. Thelancing device according to claim 4, wherein the auxiliary member isattached to the lancet holder.
 6. The lancing device according to claim5, wherein the auxiliary member and the lancet holder are attachedtogether by threading engagement, the variation of the position of theauxiliary member relative to the lancet being performed by rotating theauxiliary member and the lancet holder relative to each other.
 7. Thelancing device according to claim 1, wherein the tip end portion of theauxiliary member surrounds an entire circumference of the tip endportion of the lancet.
 8. The lancing device according to claim 7,wherein the lancing projection comprises a needle projecting from a tipend surface of the main body; the tip end portion of the auxiliarymember being provided with a patch plate portion facing the tip endsurface of the main body, the patch plate portion being formed with ahole for passing the needle.
 9. The lancing device according to claim 1,wherein the auxiliary member has a configuration capable of allowing theneedle of the lancet to project from the tip end portion of theauxiliary member entirely throughout the length.
 10. The lancing deviceaccording to claim 4, wherein the operation mechanism comprises: aresilient member for biasing the lancet holder in the housing toward theopening; a latch member for latching the lancet holder in the housingagainst resilient force of the resilient member; an operation memberexposed to an outside of the housing at least partially; and a latchrelease member which operates to release the lancet holder from thelatched state when the operation member is operated.
 11. The lancingdevice according to claim 1, further comprising a pump mechanism; thepump mechanism comprising: a cylinder and a plunger defining a pressurechamber capable of communicating with an outside of the housing throughan exhaust vent and capable of communicating with an inside of the tipend portion of the housing through an intake vent; a plunger operationmechanism for reciprocally moving the plunger relative to the cylinderby an operation different from the operation of the operation mechanism;a first non-return valve for opening or closing the exhaust vent, thefirst non-return valve keeping the exhaust vent open when the plungerreduces a volume of the pressure chamber; and a second non-return valvefor opening or closing the intake vent, the second non-return valvekeeping the intake vent open when the plunger increases the volume ofthe pressure chamber.
 12. The lancing device according to claim 11,wherein the plunger operation mechanism comprises an outer cylinderarranged outwardly on the housing for reciprocal movement, andconnecting means for connecting the plunger to the outer cylinder sothat the plunger moves reciprocally relative to the cylinder when theouter cylinder moves reciprocally.
 13. A lancing device comprising: ahousing having a tip end formed with an opening; a lancet arranged inthe housing and having a tip end portion; an operation mechanism foradvancing the lancet within the housing toward the opening; and anauxiliary member for advancing together with the lancet toward theopening, the auxiliary member having a tip end portion located fordirect contact with a portion of skin drawn into the housing through theopening; the auxiliary member being capable of varying a positionrelative to the lancet for varying a projecting dimension of the tip endportion of the lancet from the tip end portion of the auxiliary member.14. A lancing device comprising: a housing having a tip end formed withan opening; a lancet arranged in the housing; an operation mechanism foradvancing the lancet within the housing toward the opening; and anauxiliary member for advancing together with the lancet toward theopening, the auxiliary member having a tip end portion located on a sideof a tip end portion of the lancet; the auxiliary member being capableof varying a position relative to the lancet for varying a projectingdimension of the tip end portion of the lancet from the tip end portionof the auxiliary member; wherein the housing includes a sleeve rotatablerelative to another portion of the housing; rotation of the sleevecauses the auxiliary member to move relative to the sleeve axiallythereof for varying the position of the auxiliary member relative to thelancet.
 15. The lancing device according to claim 14, further comprisinga cam mechanism which moves the auxiliary member in a back-and-forthdirection of the lancet when the auxiliary member is rotated relative tothe lancet; the auxiliary member engaging the sleeve to rotate relativeto the lancet by rotating the sleeve.
 16. A lancing device comprising: ahousing having a tip end formed with an opening; a lancet arranged inthe housing; an operation mechanism for advancing the lancet within thehousing toward the opening; an auxiliary member for advancing togetherwith the lancet toward the opening, the auxiliary member having a tipend portion located on a side of a tip end portion of the lancet; and apump mechanism; the auxiliary member being capable of varying a positionrelative to the lancet for varying a projecting dimension of the tip endportion of the lancet from the tip end portion of the auxiliary member;wherein the pump mechanism comprises: a cylinder and a plunger defininga pressure chamber capable of communicating with an outside of thehousing through an exhaust vent and capable of communicating with aninside of the tip end portion of the housing through an intake vent; aplunger operation mechanism for reciprocally moving the plunger relativeto the cylinder by an operation different from the operation of theoperation mechanism; a first non-return valve for opening or closing theexhaust vent, the first non-return valve keeping the exhaust vent openwhen the plunger reduces a volume of the pressure chamber; and a secondnon-return valve for opening or closing the intake vent, the secondnon-return valve keeping the intake vent open when the plunger increasesthe volume of the pressure chamber.
 17. The lancing device according toclaim 16, wherein the plunger operation mechanism comprises an outercylinder arranged outwardly on the housing for reciprocal movement, andconnecting means for connecting the plunger to the outer cylinder sothat the plunger moves reciprocally relative to the cylinder when theouter cylinder moves reciprocally.
 18. A lancing device comprising: ahousing having a tip end formed with an opening; a lancet arranged inthe housing; an operation mechanism for advancing the lancet within thehousing toward the opening; an outer cylinder fitted around the housingfor axial reciprocal movement; and an auxiliary member for advancingtogether with the lancet toward the opening, the auxiliary member havinga tip end portion located on a side of a tip end portion of the lancet;the auxiliary member being capable of varying a position relative to thelancet for varying a projecting dimension of the tip end portion of thelancet from the tip end portion of the auxiliary member; the axialreciprocal movement of the outer cylinder causing air inside the housingto be pumped out of the housing.